Stoker mechanism having a pulsatory grate



' P. o. KocK 3,005,446

STOKER MECHANISM HAVING A PULSATORY GRATE 5 Sheets-Sheet 1 Oct. 24, 1961 Filed May 24, 1957 Oct. 24, 1961 P. o. KocK sToKER MECHANISM HAVING A PuLsAToRY CRATE:

5 Sheets-Sheet 2 Filed May 24, 1957 lNvENToR Paul O. Kock Oct. 24, 1961 P. o. KocK sToKER MECHANISM HAVING A PULSATORY GRATE 5 Sheets-Sheet 3 Filed May 24, 1957 uo/ ul" INVEN'roR Paul O. Kock Oct. 24, 1961 Filed May 24., 1957 P. o. KocK 3,005,446

sToKER MECHANISM HAVING A PULSATORY @RATE 5 Sheets-Sheet 4 C: nur un: um cnr rm' mr. mr c: I

l449m X32 K22j T45? 2 26o Y S 3 i\\\\\ EE 23 l 64 l. 1mm L ENTOR P O. Kock Oct. 24, 1961 P. o. KocK 3,005,446

STOKER MECHANISM HAVING A PULSATORY GRATE Filed May 24, 1957 5 Sheets-Sheet 5 Fig.7.

3,005,446 STOKER MECHANISM HAVING A PULSATORY GRATE Paul 0. Kock, Columbus, Ohio, assigner to Bituminous Coal Research, Inc., Pittsburgh, Pa., a corporation of Delaware Filed May 24, 1957, Ser. No. 661,376 Claims. (Cl. 122f376) This invention relates to a new stoker mechanism having a pulsatory grate for the effective burning of coals and other solid fuels including bituminous coals with caking or swelling characteristics. More particularly, this invention pertains to new automatic stoker units having a continuous fluid-cooled grate surface which is caused to pulsate with a relatively small magnitude low frequency movement to slide a fuel bed thereover without turnover thereof.

Stoker mechanisms made in accordance with my invention may be utilized for the automatic burning under varying heat demand loads of diverse solid fuels including bituminous coals having caking or swelling characteristics, or having high ash or low ash-softening temperature',

characteristics, continuously, uniformly and efliciently. If desired, my new stoker mechanism may be constructed as a removable unit to be inserted in the iirebox of a suitable boiler or my new construction may be fabricated as parts for assembly on the site where it is to be used.

Preferably, cooling is accomplished in my new stoker. mechanism by water through connections if desired, with;

the water space in a heater, furnace, or boiler. The grate in my new stoker mechanisms is continuous and relatively smooth so that a fuel bed may be caused to move thereover without turning over or materially disturbing the arrangement of particles therein. Moreover, the grate bars are relatively short and of a design which inhibits warping and other diiiculties. Direct contact between cooling tubes and fuel bed is avoided by such grate bars,A those at the ash or front section of the grate being inclined at an angle to the remainder of the grate surface for as. sistance in maintaining a desired depth of fuel bed. A,

substantially straightline pulsation preferably of relatively small magnitude and low frequency is imposed upon the grate to assist in advancing a fuel bed thereon. economical drive both for such pulsation and for feeding fresh fuel to the grate may be provided pursuant to my invention. A wind box is preferably fixed to the underside of the grate for movement therewith and is laterally partitioned for regulation of the quantity of air supplied upwardly through the grate to the respective longitudinal,

of giving long, trouble-free and relatively low cost oper ation. Other objects, features and advantages will be apparent from the following description and from the accompanying drawings, which are illustrative principallyof one embodiment of my new stoker mechanism, in which bodiment of a new stoker mechanism unit of this invention installed in a water tube boiler;

FIGURE 2 is a side view on a somewhat larger scale of the stoker mechanism unit embodiment shown in FIG- URE l, with parts broken away and partly in section;

FIGURE 3 is a view of the back end of the Stoker States Patent FIGURE l is a side view, partly in section, of one em- "ice mechanism illustrated in FIGURE 2 with a cover sheet therefor partly broken away;

FIGURE 4 is a plan view of a pulsatory drive mechanism illustrated in FIGURE 3 with the fuel hopper feed mechanism removed and as viewed from a horizontal plane passing generally through line IV-IV on FIG- URE 2;

FiGURE 5 is a view on a larger scale taken generally along line V-V of FIGURE 2;

FIGURE 6 is a further larger scale view similar to the left-hand side of the view shown in FIGURE 5 but with the sectioning plane through bolting means used to secure grate bars to the grate;

FIGURES 7 and 8 are respectively side and plan views of an entry grate bar used in the illustrated Stoker mecha nism grate;

FIGURES 9 and 10 are respectively a side view in medial section and a plan view of a combustion air grate bar utilized in the illustrated stoker mechanism grate;

FIGURES ll and l2 are respectively side and plan views of a discharge grate bar used in the illustrated stoker mechanism grate; andV FIGURE 13 illustrates a modified drive for the pulsation movement of a stoker mechanism made in accordance with this invention.

Referring to the drawings, a new stoker mechanism 10 of my invention is shown having a water-cooled pulsatory grate 11 and a fuel feed and drive mechanism 12 in the. form of an integral unit forthe rebox of a boiler 13:.

Boiler 13 is schematically shown and, for the purpose of illustration, may be a water tube type like that shown in my copending patent application Serial No. 603,088, filed August 9, 1956, now Patent No. 2,827,023. Boiler 13 as shown is provided with a regulatable blower assembly 13a to supply combustion air under pressure to stoker 10 and,

if desired, a regulatable induced fan stack draft mecha nism 13b may also be provided.

Stoker 10 may be mounted on wheels for readiness of insertion as a unit in a boiler or it may be assembled in situ. In the illustrated embodiment, after stoker 10 is in place, an upper transverse header pipe 14 is connected by a pipe 15 having a iiexible section 16 to a boiler pipe 17. In like manner, a lower transverse header pipe or manifold 18 is connected through a pipe 19 having a flexible section 20 to a boiler pipe 21. The boiler pipes 17 and 2l open into the water space of boiler 13 with water circulation preferably being into manifold i8, thence through longitudinally extending grate cooling tubes 22 and out of manifold 14, returning to the boiler water system through pipe 17. The cooling tubes 22 extend longitudinally and parallel to one another and the respective upper and lower ends of such cooling tubes ZZ communicate with the interiors of the manifolds 14 and 18. The presence of the flexible pipe lengths 16 and 20 permit grate 11 with its transverse headers 14 and 18 and its cooling tubes 2.2 to be moved back and forth virtually with straight line motion through a distance of relatively small magnitude at a relatively low frequency without interfering with the iiow of cooling fluid through the grate 11 or boiler 13.

Stoker 1li is provided with a rigid structural frame having horizontal members 23 and vertical members 24, the rearward end Z5 of such frame being enclosed by cover sheets 25a and serving as a driven compartment for the pulsatory movement imposed upon grate 111.v

in a forward direction so as to be substantially parallel to .the slope of grate 11. In the illustrated embodiment, grate 1l may be provided with a six degree slope from the horizontal to avoid any steam binding in the horizontal rea'ch of the coolingtubes 22. The side plates 26 are parallel and extend for substantially 'theentire length Vof grate lll, terminating adjacent an 'ashpit v27 al the forward end of the irebox of the boiler *13. Ash pit V27 may be provided with a remotely controllable 'conveyor 27a to provide for mechanical removal of ashes. Each side plate 2o is adjacent a respective side wall '2S in lthe lireboX of boiler 13 so that whatever solid rneterial may fall from a fuel bed on grate lil will fall in and "close the space between such respective side plates 256 and adjacent side walls 28.

Grate 1l is provided with a frame having .longitudinally extending angles 29 aixed to cross angles Sti. The longitudinal angles in turn have the iianges thereof extendedupwardly by llange extensions 31, the lower edges of which are welded to the angles 29 respectively. Cross members 32 of T=shape in the illustrated embodi ,tent are welded to the vertical flanges ofthe cross angles 'Qdi-and like `Tmember 34 at the entry end 33 of the frame of grate di is supported .at the ends lby extensions 3i.

Transverse angles 35 and di) are welded at the tends to side extensions 3l. Flexure plates36 and 37 are provided and fastened 'at the respective bottoms ythereof to respective vcross members '33 of Vthe rigid Stoker frame, bars 39 being utilized to serve as bolting pads with the lower ends of the respective ilexure plates 35 and 37 secured between such bars 39 and the cross members 3?,-

a's shown in FlQUB-E 2. Theexure plates are substantially vertical 'and 'support grate ll for 'alternate jpulsation v'movement and rests without Ymovement between such pulsations inthe `course 'of va continuous operation of stolzer mechanism il?. The upper 'ends of therespective flexure plates are bolted to cross angle Ail) Yand to the foremost VT member 32, keeper bolting bars 41 being employed with suitable bolts, lock washers and nuts for the purpose of movably mounting grate il 'on the flexure plates 36 and 37. instead of 'grate lllbeing mounted on lleXure plates 36 'and'37 it may, if desired, be suspended from hangers pivotally connected vto the framework of boiler 13 or its foundation.

The 'cooling tubes 22 are welded around their respective ends to the manifolds ld and land the horizontal reach f such tubes is supported by 'and rests upon the T-shaped members 32 and 34 and upon angle 35. Grate bars 42 which may be made of cast iron and side grate bars 43 are positioned in cross rows around the upper portions of tubes 22 andin the longitudinally extending spaces adjoining the outsides of tubes 22 inclusive of the spaces on the innersides of the respective vextensions 3l of the grate frame. Each such grate bar is provided with a depending portion 44 which is upwardly drilled and tapped in registry with openings in the members 32, 3d and .35 so that socket-head bolts i may be passed through such openings in such cross members'to respectively threadably engage such grate bars. Loek washers i6 are also so provided so that as the bolts 4S are tight-- ened the respective rows of grate bars 42 and 43 are 6 drawn tight against the cooling tubes or tubes 22 adjoining them. The side of such bars adjoining any such tube 22 is provided with a iillet 47 conforming tothe curvature of the adjoining portion of the Vcooling tube ZZupon which the respective 'grate bar seats. Preferably, a heat conducting breakable cement or other heat conducting material Amay be placed between the fillet 47 and the tubes Z2 in the course of assembling a new grate l1, for increased heat transmission through the intersurface area. The'heads of the respective grate bars 42 and 43'broaden out as shown in FIGURES 5 and v6 and yare separated from adjoining grate bars by a slight space 48 to take care ot' expansion and contraction which occurs Vin the course of use of such a device. Grate bars 43 along the sides of grate lll have a'laterally outwardly extending -ange 49 ltocover the `space between the sides 31 of the grate 1l and the side plates 26 to keep material from passing into the space between the respective members 31 and 26. If desired, a flexible seal, like strip 26a, may also be inserted Yin :such space. It will thus be noted thatthesur'face llofgrate 11 uponwhich the fuel bed lies .iscontinuousand .acts as a unit. Surface 50 is made up of aplurality of Vgrate bars 42 and 43 placed [in side-by-side cross rows and in end-to-end columns which move as an .entirety .in the course of the relatively straight-line pulsatory movement of grate 11.

The grate bars 42 and 43 are differently formed in the illustratedembo'diment for the respective 'transverse row sections -A 'of 'the Jgrate. Thus, in the entry section, the -grate bar-s 42u and 43a are imperforate andhave upper surfaces inclined downwardly and forwardly `with.

a l'argetransverse recessed portion 5l on the underside thereof'tolit over'theitop oi vmanifold i4 and a rearward apron '.52 `to tit closely beneath thefdelivery end :of Afeed tubes 53 in the fresh fuel feed mechanism ,12. In 'the next transverse section B, grate bars @2b and 43b toward therear `of grate 11`are imperforate like the entry section `grate bars (42a and 4351) 'so that that portion of the duel, "like bituminous coal,'resting on grate bars '42h and43'b and falso Yon `bars-42a Pand 43a tends to give up its Yvolatiles while inltlrose portions of the 'surface y,50 of grate '11. Such volatiles released from the ffuel lbed will iquickiy be burned in the hot gases generated'in the lireb'oxvfandxpassed'through 'the vboiler in the course ofits use.

and 43d areiin 4the :second 'transverse combustion 'airfse'etion .and '-a stilllfurther like row 'of Vcombustion air grate bars 42e andf43e is inthezpenultimate transverse section.

These combustionair grate bars (see FlGURES *.9 'andv while the depending portion 4f is curved downwardly to .conformto the .curve at the front ends of the cooling tubes 22, a .bolt 'opening 56 being provided to pass alongside .such tubes and fasten .that end of the grate bars 42f1and 43j ,to across angle bar S7 by means of bolts, lock 'Lwashers and nuts passing between the respective cooling .and support itubes 22. The upward inclination of the anges l5.5 across the vwidth otsurface Sii` assiststin maintaining a fuel bed of the desired thickness :and fin discharging :ash gfrom grate l1 ,into ash pit 27 as theiu'el bed .is ed .forwardly 'on grate Il .during the pulsa'tory movementsthereof.

Combustionair .may be supplied to the transverse :row sections .marked C, D and E having .the respective grate .bars with the respective suixes 0, d and e in the .foregoing description. Such combustion .air reaches such .sections of the Vgrate Vfrom a plenum .or wind 'box 58. Wind box 58 has an outer shell 59 and is .internally laterally divided .by partitions ell and 51. Flanged 'openings 62 in the two forward compartments communicate with a stationary combustion air duct 63, duct 63 having a flanged registering opening opposite each 'of the flanged openings 62. Tubular sleeves '74 which :may be made of berglass impregnated with "a material like neoprene 'extend between the flanged openingsS .andtheLrespective openings 62 to form respective 'flexible sealed Vconnections so that .movements of grate :11110 :not move duct 63. Moreover, the branch openings in duct `63 `in registry with openings 621respejctively may be provided with dampers to apportion air Undergratefcombustion 'air grate bars 42C and 43`c'a1'e in `ithe first .combustion air "section, like grate bars 42drespectively supplied to the compartments C and D. Further regulation may be obtained, if desired, by the employment of an automatic damper in the circuit of a` blower fan 71 used to supply combustion air to duct 63. And, inthe illustrated embodiment an auxiliary branch duct 72 connected to duct 63 may be opened and used to provide overiire combustion-air to the rebox through parallel transverselyv spaced nozzles 73.

The partitions 60 extend from side-to-side of box 58 and from the bottom thereof to a respective cross angle 64 in the upper rectangular structural rim 65 around the open'top of compartments C and YD in box 58. The horizontal angesof the angles of frame 65 engage mating surfaces on the underside of the frame of grate 11 so that box 58 may be secured to the frame of grate 11 by suitable bolts and nuts. As a consequence, movement of grate 11 causes wind box 58 to move therewith since it is supported by and depends from grate 11. Par-l tition 61 is provided with an opening 66 for which there is a hinged door 67 which normally is kept partially open by an adjustable spacing member 68. Combustion air entering opening 62 of compartment D will pass into the fuel bed resting on the grate bars 42e and 43e and also will pass through opening 66 into section E when door 67 is open and then into the fuel bed through the openings in grate bars 42e and 43e. i

Fresh fuel. is fed across the entire width of grate 11 to the entry section grate bars 42a and 43a thereof by fuelfeeder mechanism 12. As shown, the feeder mechanism is provided withan enclosed cubical frame 75 open at the top for the receipt and support of a transversely extending chute 76, the lower end 77 of which substantially closely and separately embraces a plurality of parallel feed screws 78 inclined downwardly in a forward direction. A hopper 79 may be supported above chute 76 by frame 75 and be provided at the top with an opening 80 to which a solid fuel like bituminous coal may be supplied manually, or automatically as by means ot'anautomatic conveyor. The forward end of each feed screw `78 is separately enclosed within a feed tube 81 as a continuation of the chute 76. The feed tubes 81 fit the screws rather closely and at least one full'flight at the forward end of each screw 78 is within its tube 81 to act as a tire wall and inhibit any burning back into chute 76,. To assist therein and provide relief against any binding tendency, the feed screws 78 may be tapered n a rearward direction away from grate 11 or the diameter or pitch of the flights more directly under the chute the forward end of each shaft 83 there is aixed a` sprocket 87, a shear pin 88 being used to connect it to its respective shaft 83. Hence, if any feed screw 78 should jam, it would shear its own pin 88 only and the sprocket thereof would rotate idly without immobilizing the other feed screws 78. A chain 89 engages all of the sprockets, a guide 90, an idler roller 91 and a drive sprocket 92 so that as drive sprocket 92 turns, fresh fuel from hopper 76 is fed on to the rearward or entry end A" of grate 11 by the screws v78. Such screws as shown are of alternately opposite-hands so all feed fuel forwardly-when rotated by gear 92. As fresh fuel is fed by mechanism 12, it passes through a refractory lined tunnel 93 which bridges the space between the end of the de livery tubes 81 and the iirebox opening 94 in boiler 13.

In the drive'compartment 25 of mechanism 12, an'electric motor 95 is fastened to a slidably adjustable base 96 secured to the frame of stoker mechanism so that the desired tension may be imparted to a belt 97 used to drive a driven pulley 98. Driven pulley 98 is mounted on a shaft 99 journaled in bearings held by rigid brackets 100, the other end of shaft 99 being provided with a pulley 101 which serves to drive a further belt 102. Belt 102 also engages a large pulley 103 mounted on a shaft 6 10 4 journaled in the frame of compartment 25. A pulsa-1 tion cam 105 is affixed to shaft 104, such fca'm having a2 smoothly contoured cam rise portion 106 and fall por- 109 from which a cam lever 110 is pivotally supported,

the lower end of lever 110 being provided with a cam follower roller-111 held against the periphery of cam 105 by a spring 112. Pull rods 114 are attached at their forward ends to grate 11 and are provided with spring re` tainers 114e at their respective rearward ends. The pullrods 114 pass through brackets 100e rigidly connected to the main brackets and a spring 116 surrounds eachrod 114 in compressed relation between its respective' bracket'100a and retained 11461 to maintain grate 11 in pressing connection with the periphery of cam through a connector 113 and lever 110. Connector 113 is pro-- vided with a registering hole to receive a pivot bolt 115- which passes through registering openings in lever 110 to` pivotally connect member 113 to cam lever 110. The movement in operation of connector 113 is preferably so small'that grate 11 is virtually reciprocated in a straight line. The forward end of connector 113 is rigidly connected to an anglepiece 117 which in turn is fastened toI cross angle 40 between the laterally spaced ilexure plates 36. Hence as connector 113 is moved back and forth by the rotation of cam 105, grate 11 reciprocates with a pulsatory short straight-line movement so that a fuel bed slides over surface 50 during operation toward dischargeend F without forwardly jumping or turning over the bed or portions thereof. The rise portion 106 of cam 105 is preferably smoothly contoured to provide smooth acceleration and deceleration during the stroke of connector 113 in each direction, with the greatest travel per given time occurring at the ash pit ends of respective strokes. In this way, grate 11 has its maximum speeds as it nears the final portion of its forward stroke toward the ash pit 27 again as it initiates its return stroke from such forwardmost position. Further, although surface 50 of grate 11 is provided, as shown, with about a six-degree slope away from the horizontal extending downwardly in a forward direction in the embodiment shown to insure avoidance of steam binding, grate 11 will function to move the fuel bed during a pulsatory portion of an on cycle even when grate 11 is horizontal because of suchf in each direction. Byrvarious means including a combus-v tion control and timer device 118 connected to a power source 119, the fuel feed and pulsatory operation period in an on cycle and the on cycle duration in stoker mechanism 10. may be respectively and widely varied. Thereby, the length of on period vand the frequency and length o f the pulsatory operation of grate 11 in such an on period will correlate to satisfy any heat demand load including holdres that may be required of stoker mechanism 10.

A gear reducer 120 is pulley driven from shaft 104 byl a belt 121. Drivesprocket 92 is connected to the output shaft of gear reducer 120 with the result that chain 89 is' moved to feed fresh fuel onto the grate bars 42a and 43a Whenever motor 95 is energized to commence a furthery pulsatory grate movement period. Since the operation of the feed screws 78 is positive, fuel will thereby be supplied uniformly to the grate across the width thereof. In theevent that it becomes desirable to insert a tube cleaner in the grate supporting and cooling tubes 22, plugs 128 in manifold 14 respectively opposite the forward ends of each of such cooling tubes may be removed accende for-that purpose. Further, the rearmanifold vr18rnay--la`e provided with a suitably valvedfblowc-ifordrain pipe A129 for use as occasion requires.

.fAn alternate drive mechanismto thatlin compartment 25.1is schematically illustrated-in FIGURE -l3. ln that figure, an electric motor 130 when-energized during-a pulsatory grate movement period rotates aldriveshaft 131 through a iiexible coupling 132. `Shaft Y131 -may be mountedin bearings 133. An 'eccentricf134 is secured to shaft 131 to rotate therewith. A -rock vshaft V135 is mounted in bearings 136. vA rockable eccentric 137 is amxedto shaft l35. A-crank yarml138 embraces-the eccentrics-ISS and 137 to rock eccentric-137in-the illustrated embodiment through an angle such as 90 which-is bisected by ahorizontal plane through-theaxis of rock shaft liS. A drive eccentric 139^isalsofkeyedto shaft 135 and has its center.angularlydisplacedbysan lamount such .as 45 from the centerlof the-rocking-eccentric -l37. Drive eccentric 139 ispivotally connected-bya-COnneCtor 149 to an angle 141 correspondingin-function to angle 117. Hence, as shaft ll is rotated in the .direction of arrow 42, the maximum Aspeed of the -pulsatory grate (like Vgrate 1i) `of which angle 141 is apart, will occur during that portion of the stroke in eachfdirectionaadjoin ing the foremost position of angle `ldd-audits grate which is when such grate is farthest Yfrom the "axis ofrock shaft 135. Moreover, such pulsation will Abe ofrrelativelysmall magnitude and low frequency and Lthe fuel -bed-on the grate to which angle M1 Vis connected will not jump or turn over in the course of such pulsation but will Ybe virtually straight-line motion with smooth speed change transitions throughout vand at the ends of ltherespective strokes where the direction Tof movement -of the -grate `is changed.

AIt will Abe evident that Stoker mechanism of my invention may be made with various mcdications in the provisions for driving the same and in the elementsandtparts thereof without departure from'myinvention. Further, stoker mechanism made in accord withvmyinvention may be used with a variety of different kinds of boilers and other equipment. ln some cases, coolingof lmy-new grate may be performed by a gas under pressure rather than by liquid. These and other changes are within the spirit of my invention and the scope ofthe appended claims.

I claim:

1. In a stoker unit, apparatus comprising, `in combination, a stoker frame, a unitary water-cooled pulsatory grate inclined somewhat downwardly toward its discharge end, a grate frame in said grate, a plurality ofparallel longitudinally extending cooling ltubes mounted on said grate frame, upper and lower manifolding headers connecting the ends of said cooling tubes respectively, cXure plates respectively connected to said stoker frame Aand to the respective ends of said grate frame to movably support said grate, grate bars in side-by-side transverse row sections and end-to-end columns providing a substantially continuous smooth gratesurface, said .grate bars being generally T-shaped in cross section and having a depending web to fit between and alongside said cooling tubes, the undersides of the T-heads of said grate bars generally conforming in shape to the adjoining surface of said cooling tubes respectively, heat conductive-means in the intersurface area between said grate bars and said cooling tubes respectively, means for-rigidly connecting the underside of said grate bars to said grate frame, said grate bars at the entry end of said grate being imperforate, more forwardly transverse row sections of said grate bars being perforate and provided with vcombustion air discharge tuyeres directed generally upwardly and vlongitudinally toward the discharge end of said grate, a-transverse row section of grate bars at said discharge end having a flange inclined somewhat upwardly and forwardly relative to said grate surface, said Agrate frame below said transverse row sections of perfora-te wgrate -bars being divided generally into separate compartments, a compartmented windw'boxsuspended vfrom Vsaid -grate frame,

endof the'rearmost rowof grate bars, feed screwsextend-A ingalong-said troughs landlinto said-feed tubes respec-A tively, adjoining feed screws being of opposite hands, common means for-driving -all of said feed screws in a fuel feeding direction, shear meansfrespectively connect-,- ing saidlfeed screws =t`o said commonfmeans, said feed screws having theirforward sections-fittingclosely in said feed tubes -and with-the rearward portioniof said feed screws being of lesser V-feed capacity, pull Vrod means adapted-to urge said :grate-toward'its-srearmost position, aconnector-rigidly connected to said grate,-a camflever pivotally connected to -said connector, a cam to operatively -exertforce'against said cam lever, saidecam'having a -smooth Vcontour periphery Lincluding 1a r'ise portion adapted'toprovide :greater average speed ofmovement of sad :grate at the respective 'rearmost end of its pulsatory strokes in both directions when said cam is rotating, and -means 'for simultaneously'rotatingsaid camand driving'said common means.

2. lIn 'a stoker mechanism, apparatus comprising, 'in combination, `a {pulsatory ygrate having an 'entry end, a plurality of Aparallel longitudinally 'extending'cooling tubes in-'said grate, transverse Amanifolds connecting the respective yends of said cooling tubes, means tosupport 'said gratefor pulsatory movements thereof, grate bars insideby-side ltransverse 'row -sections and end-to-'end columns providing -a -substantially continuous smooth grate lsur'- face, said grate bars having a depending portion to "fit between Aand alongside said cooling tubes, said lgrafe barshaving lleted undersurfaces generally conforming in shape to the vadjoining surfaces of Vadjoining cooling tubes respectively, said Vgrate bars at the entry end of said grate being imperforate, other transverse row sections of said grate bars being perforate and providedwithtuyeres directed generally upwardly and longitudinally toward the Vdischarge end of "said grate, -a trahsverse'row section of said grate bars a't said discharge end having afsoni'ewhat upwardly inclined apron, 'a compartrnented 'wind box suspended below :said -perforate 'grate bare, means for supplying combustion Aair to said compartments in said wind box, a fresh fuel chute at 'the entry -end of'said grate having transversely adjoining parallel longitudinally extending troughs in -the bottom lthereof and feed tubes respective end of at -least its stroke toward said entry 13nd and means for rotating said cam,a'nd means `fo`r-rotaing said feed screws, whereby said grate is lmoved back and forth in a vsmooth pulsatory virtually -straight-line path to advance a fuel bed 'over said grate 4surface without jumping or turning over ofthe same.

3. ln a Stroker unit, apparatus comprising, lin cornbination, a cooled smooth unitary pulsa'tory grate, 'means to vsupport said Igrate adjacent its ends only for pulsato'ry movement thereof, a plurality of 4vcooling tubes in said grate, means for circulating coolant through said cooling tubes, a ,plurality of Vgrate bars in side-by-side and endto-end arrangement to provide a substantially 'continuous relatively smooth -grate surface, said grate bars being generally shaped on the underside to t against said cooling tubes, a preponderance of said grate bars being perforate to supply combustion air upwardly therethrough,

a wind box supported by and below said grate to supply said combustion air, said Wind box having a transverse partition, a chute for fresh fuel having parallel longitudinally extending troughs in the bottom thereof, feed tubes at the forward ends of said troughs and overlying the grate bars across the entry end of said grate, transversely adjoining feed screws in said troughs extending into said feed tubes respectively, common means for driving all of said feed screws in a fuel feeding direction, breakable means for each feed screw respectively to transmit force to said feed screws from said common means, and smooth contour means operatively connected to said grate to drive said grate back and forth with a relatively short pulsatory substantially straight-line movement.

4. In a Stroker mechanism, apparatus comprising, in combination, a longitudinally movable grate having an upper side and an entry end, a plurality of longitudinally extending feed tubes transversely adjoining one another on the upper side of and substantially across the entire width of said grate at the entry end thereof, a plurality of longitudinally extending feed screw relatively closely tting in at least a part of said tubes, a shaft for each of said feed screws extending in a direction away from said grate, a shearable drive member operatively connected to each of said feed screw shafts, means for feeding solid fuel to the ends of said feed screws farther from said grate, and a common means to move said grate and rotate i 10 said feed screws for synchronized feeding of fuel in a positive manner.

5. In a stoker mechanism as set forth in claim 4, having alternate ones of said feed screws of opposite hands, means'whereby said common means drive said feed screws of opposite hands in opposite rotational directions, means for spacing the ends of said feed screws nearer said grate from the rebox zone thereof, and tunnel means extending between said ends and said zone.

References Cited in the file of this patent UNITED STATES PATENTS 220,901 Dillon et al. Oct. 21, 1879 786,123 Hess Mar. 28, 1905 1,219,256 Cooke Mar. 13, 1917 1,840,117 Losch Jan. 5, 1932 1,886,064 Steinmuller Nov. 1, 1932 2,086,760 Wood July 13, 1937 2,116,322 Muir et al. May 3, 1938 2,387,383 Bennett Oct. 23, 1945 2,763,220 Becker et al. Sept. 18, 1956 FOREIGN PATENTS 775,771 France Oct. l5, 1934 3,808 Great Britain Aug. 10, 1882 352,358 Great Britain July 9. 1931 129,284 Sweden Aug. 29, 1950 STATES PATENT OFFICEk CERTFICATIN F CORRECTION Patent No, stoof-446 october 24,1961

Y A I I Paul O. Kock I i It is hereby certified that error eppears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant, linev l, for "Paul O.. Koek read Paul O. Kock Column 4m line 14, after sectionsL strikey out "A and insert d the :same after "section" same line 14" same column; column 8, line 47, for bare read barsten" Signed and sealed this 3rd day of April 1962.

( SEAL) Attest:

ERNEST W. SWIDER l DAVID L. LADD Attesting Officer -l Commissioner of Patents A 

